Numerical simulation of flow structures around an oscillating rectangular cylinder in a channel flow

Abstract

In this paper, the flow structures of a confined flow over a transversely oscillating rectangular cylinder are investigated numerically. The flow characteristics are dynamic and are classified as a moving boundary problem. An arbitrary Lagrangian-Eulerian (ALE) kinematic description method is used to describe the flow field and a Galerkin finite element formulation with moving meshes is employed to solve the governing equations. The effects of the oscillating speed, frequency and aspect ratio on the flow field are examined. The initiation and subsequent developments of the vortex shedding are investigated in details. The results indicate that the vortices shedding from the rectangular cylinder are entrained by the motion of the rectangular cylinder, and the interactions between the oscillating rectangular cylinder and shedding vortices dominate the state of the wake. The vortex shedding frequency is gradually changed to match the rectangular cylinder oscillating frequency, and the flow field may approach a periodic motion with time. The mechanisms of the vortex shedding from an oscillating rectangular cylinder are different from those of an oscillating circular cylinder.